The present invention relates generally to concrete anchors. More particularly, the present invention relates to an improved one piece threaded anchor for use in concrete.
Concrete anchors are well known in the art. One type of anchor is a screw anchor. Such an anchor has a shank with an external thread. The anchor is threaded into an opening or bore drilled into the concrete. The threads engage the wall of the opening and hold the anchor in the concrete. The holding strength (also referred to as resistance to pull out), depends upon the engagement of the threads with the concrete.
Another type of anchor is a multi-piece anchor that includes a bolt or like element (having a shank) with a diverging (shaped) end and a sleeve or wedge elements with a shape complementary to the anchor end. The sleeve or wedges expand outward to engage the inside of the opening as they are urged outward by the complementary shaped elements.
Screw anchors serve their function well, however, when the concrete around the screw anchor is cracked, problems arise with respect to meeting pullout requirements. As for the multi-piece anchor systems, these function well, however, they are significantly more complex and costly compared to screw type anchors and installation is more labor intensive.
Accordingly, there is a need for a concrete anchor that is readily installed and can meet today's pullout requirements. Desirably, such a fastener is a one-piece fastener and functions well and meet requirements even installed in concrete with a crack in-line with the fastener body.